Ultra-tall skyscrapers continue to redefine the skylines of Shanghai and Dubai. One World Trade Center is now reaching completion in New York City, having recently topped out as the tallest building in the U.S. There can be no doubt that we are in the midst of another golden age of the skyscraper. After a long lull, architects are once again pushing the boundaries of height.

This new batch of behemoths have benefitted from incredible developments in planning and engineering, allowing them to be more sustainable and efficient than ever. Some function more like cities than office buildings, with unbelievable density and adaptability of use. In fact, as the last installment of Amazing Buildings reported, Gensler’s Shanghai Tower—currently the world’s second-tallest building—is geared to gain LEED Gold certification upon its completion.

However, important architecture is not always about creating completely new structures. Sometimes the greatest design challenges lie in improving pre-existing work. In 2009, the Sears Tower, one of the United States’ most iconic buildings [and at the time its tallest] was rebranded The Willis Tower in a deal with the London-based Willis Group Holdings. But the name wasn’t the only thing set to change.


The 1,450-foot building, designed by Skidmore, Owings & Merrill, was still a marvel of engineering in 2009. It had held the title of world’s tallest building for twenty-six years and had entered popular consciousness. Nevertheless, its 1973 completion date meant that sustainability and energy efficiency were not its strongest assets. The new management of the Tower turned to the firm of Adrian Smith + Gordon Gill Architecture [whose principals had recently left the building’s original design firm, SOM], to initiate a massive and wide-ranging study to modernize and increase the efficiency of the landmark building.

Smith and Gill’s greening study for the building is shocking in its ambitious scope and proposed effect. This should come as no surprise. With 416,000 square meters of building area and 104 floors, there’s a lot of room for improvement. The project promises an 80% reduction in the tower’s base electricity use—68 million kilowatt-hours or 150,000 barrels of oil worth of power. As with many efficiency schemes, the bulk of the project focuses on insulation: the 16,000 single-pane windows would be replaced, resulting in a 50 percent reduction in heating energy. New gas boilers, powered by fuel cells, would generate electricity and regulate the building’s temperature at nearly 90% efficiency.

The study also proposes a massive water use initiative that would result in 24 million gallons of saved water annually through condensation recovery and plumbing upgrades. Water for the building’s bathrooms would be heated by the highest solar panels in the United States, on the proposed green roofs of the building.

Perhaps most impressively, the architects also proposed the construction of a 500-unit, 5-star, LEED Gold-certified hotel addition to the tower. With strategically placed wind turbines and energy-efficient double-walled construction, the addition serves as a model of how far thinking about sustainability has come since the 1970s.


As of today, the study’s actual implementation remains incomplete. Retrofitted plumbing has accounted for 10 million gallons of saved water annually and a green roof on the 90th floor is being used to test stormwater collection and reducing the urban heat island effect. And while the study remains largely theoretical, it still serves as a model for the possibilities of retroactive sustainability projects, even on a massive scale. Rather than simply rip-ping up and starting again, this type of engagement with careful energy analysis can significantly reduce maintenance costs for building owners and have huge environmental implications. If all of Smith and Gill’s recommendations were to be implemented, the Willis Tower would save the energy equivalent of the annual electricity usage of 2,500 average Chicago homes or five million miles of highway driving.

With such rapid advances in sustainability technology, it seems clear that we must design with obsolescence in mind. In terms of efficiency, a building will never be completely finished. There will always be methods to streamline and improve energy consumption on the horizon. The trick is to design with an eye for their eventual implementation further down the road.

Sustainability should now simply be regarded as a good business practice. On the strength of their work in sustainable design, Smith + Gill was recently awarded the bid to design the 2017 Astana World Expo in the capital of Kazakhstan, themed around Future Energy. The 173-hectare site will be powered completely by wind and solar power.

By 2019, Smith + Gill’s Kingdom Tower should be finished in Jeddah, Saudi Arabia. While the exact measurements are still private, it is expected to be the tallest building in the world and will come at a cost of at least $1.23 billion. Its sustainability initiatives have yet to be announced, but we know that such an ambitious project, and future massive projects like it, will need to keep efficiency at heart to be feasible. Otherwise, it will mean retrofitting in the future.

Originally Published in:

THE NETWORK / MARCH 2014 – Amazing Buildings